IWW3, 2013, Session -3 CHAIRMAN Prof. P. B. S. Sarma Prof. P. B. S. Sarma
formerly
:
1. Project Director, Water Technology Centre & Chairman, School of Resource Management INDIAN AGRICULTURAL RESEARCH INSTITUTE
New Delhi & 2. Professor Emeritus, Civil Engineering Deptt., IIT, Delhi 4/1/2013
Prof. PBS Sarma
CONCEPT OF WATER USE EFFICIENCY (WUE) IN IRRIGATION Generally defined as: “ Socially beneficial reduction of water or water loss through optimal use over medium to long term horizon taking into consideration external social ,environmental and economic effects of water use (CWC Draft Guide lines for WUE-2010 ) It is all about careful management of water supply through use of water saving technologies, reduction of excessive demand and other actions. P.B.S.Sarma
Concept of WUE-2 A recent view point is to adopt Water accounting approach. In this water delivered is divided into Water Consumed Water Not Consumed. Further each of these components are subdivided into Water put to beneficial use and Water put to non-beneficial Use This view point is appropriate for assessing WUE for a total hydrologic basin , rather than at farm or project level level P.B.S.Sarma
WUE is defined in Many ways Social Scientists: Value of agricultural produce (kg) per Unit of water used in production of the produce Engineers & Agricultural Scientists: (A Ratio) Volume of water used by plants through ET per unit of water applied from a source P.B.S.Sarma
Engineers’ accounting for losses in irrigation system (ICID) Conveyance Efficiency (Ec): ( in Main & branch canals, distributaries, and minors) = Water received at the field inlet to a chak (block of fields) / Water drawn from the source ; Field Channel Efficiency (Eb): = water received at the field inlet / water received at the inlet of the chak (Cluster of Fields); Field Application Efficiency (Ea): = Water directly available to the crop / water received at the field inlet; Project Efficiency (Ep): Ea x Eb x Ec P B.S.Sarma P.
CAUSES OF LOW WUE-1 ► Traditionally irrigation systems were designed mainly for protective and not productive irrigation ►Water delivery systems are supply based and not demand based ►Systems not equipped for modern intensive agriculture based on HYV crops, multiple cropping with high nutrient dosages ►Soil-water-plant -atmospheric interactions not adequately considered ►Unscientific water management practices & low water charges P.B.S.Sarma
Causes of Low WUE-2 ► Prolonged periods of construction of Irrigation
Projects (15-25 years)
►Faulty land preparation & design of distribution System, ►Inordinate delays in completion of on-farm development (OFD) works ► inadequate maintenance of the distribution system -►Absence of participation by beneficiaries. ►Lack of awareness among users on the need for economic and efficient use of water ►No systematic periodical performance evaluation
P.B.S.Sarma
How to Enhance WUE? - Structural Measures-1 Conveyance system:
►Proper construction and periodic repairs & maintenance , ►Selective Lining , rehabilitation and restoration of irrigation structures Application system: ► Laser leveling of fields- water savings upto 20% in paddy and 35% in wheat, ( by reducing percolation losses), ► selective lining of water courses and field channels, ► provision of adequate drainage system, ► Adoption of greenhouse technologies . etc. P.B.S.Sarma
How to Enhance WUE? Non-structural Measures-1 ► Scientific approach to irrigation scheduling, ► Efficient methods of irrigation application ( Furrow and ridge , surge, sprinkler, drip etc., AWD,SRI and DSR cultivations etc., ) , ► Weather advisories, IT enabled agri. extension services, ► Timely repairs and maintenance of OFD works . ► Adoption of PIM through WUAs, ► Autonomy and adequate legal powers to WUAs P.B.S.Sarma
How to Enhance WUE? Non-structural Measures-2 ► Bench marking , water auditing and Periodic performance evaluation, ► Evaporation control by mulching, ► Adoption of Conjunctive use of various sources of water, ► Incentives (as in 12th Plan), for adopting efficient water management techniques, ► Adoption of less water loving varieties, etc,. ► Training of farmers in in efficient water management , ► Proper pricing of water charges, with assured water supplies P.B.S.Sarma
Adoption of Modern Technologies for improving WUE ► Adoption of Remote Sensing, GIS, Simulation and Optimization, Expert Systems, Neural Networks etc., ► IT enabled Extension services for efficient Water Management , ► Automation of canal operation, micro irrigation, ► Use of Biotechnology for development of crop varieties that use less water and are salt and stress tolerant, ► Bio-remediation and phyto-remediation technologies for waste water treatment. etc.,
P.B.S.Sarma
CONCLUSIONS The traditional concept is specific to various levels of the irrigation system. ► WUE can be quantified for farm and project levels in terms of measurable quantities, unlike in the case of water accounting approach . ► Further, there are well identified reasons as well as remedies for low WUE. ► However, the value of “Efficiency” can be more than 100 % if the contribution of soil moisture is also accounted for the water expended for consumptive Use. ► Hence replacing the expression “Water Use efficiency (WUE)” with “ Water Use Ratio (WUR)” appears reasonable. ►